In order to facilitate the examination of internal body cavities with an external orifice, it is sometimes necessary to employ an instrument to dilate the orifice and the cavity. Such instruments are called specula. Specula for examination of the cervix employ a pair of paddles or blades which are inserted into the vagina. The paddles are then separated to dilate the vaginal orifice and permit examination of the cervix. Ideally, the articulation of the paddles of a vaginal speculum encompasses three distinct movements. One is a rotational motion around one end of the paddles to provide an angled opening between the paddles which accommodates the internal topology of the cavity. A second motion is the linear separation of the paddles to cause adequate dilation of the cavity for examination. The third motion is a retraction of the upper paddle relative to the lower paddle to avoid scrapping the upper inner surface of the cavity.
In prior art specula, one of which is disclosed in W. P. Murphy Jr., U.S. Pat. No. 3,246,646, granted Apr. 19, 1966, all three of these desirable motions were not always accommodated. More importantly, each of these motions required, in the prior art, separate and independent adjustments by the user, a clumsy procedure which prolongs the examination and often causes discomfort to the examinee. Finally, prior art specula made of inexpensive plastic designed to be thrown away after a limited number of uses, require a substantial number of independently manufactured parts, tend to be flimsy due to the motion adjustment mechanisms, and often broke while in use.